A sheet material comprising an aromatic polycarbonate resin is widely used in a variety of industrial fields (such as fields of building materials and automobile parts) due to its excellent properties including dimensional stability, impact strength and transparency. Heretofore, the sheet material has often been fixed to another material by a method comprising binding a portion of the sheet material such as bolting. In this case, the other material to which the sheet material is fixed is generally a member having a lower linear expansion coefficient than that of the aromatic polycarbonate resin, e.g., metal, concrete and wood. Accordingly, there is a problem that stress concentration occurs in the vicinity of the binding points of the fixed sheet material due to a difference in dimensional change occurring along with a change in the temperature of the surrounding. The stress concentration causes a breakage in the vicinity of the binding point when it is severe.
As a solution for the problem, it has been attempted to reduce a dimensional change caused by temperature by addition of a filler to the aromatic polycarbonate resin. However, in order to obtain a sufficiently low thermal expansion coefficient by the method, various characteristic properties expected of the aromatic polycarbonate resin are often sacrificed. Thus, it is difficult to say that the method is a general-purpose method. The method is not an appropriate method especially in applications in which transparency is required. In recent years, a large-size sheet material is strongly demanded, and the above problem of stress concentration caused by a difference in thermal expansion coefficient tends to become more serious.
As a method for solving such a problem, a method which comprises binding a molded article formed from a thermoplastic resin composition to other member over a wide area by use of a rubber adhesive as a buffer layer is already well known.
Meanwhile, an attempt to shift from large-size transparent members (large-size transparent sheet materials) such as glazing materials which have heretofore been made of glass to lightweight transparent plastic sheets is vigorously made in recent years, especially in the field of glazing materials for vehicles. As the transparent plastic, aromatic polycarbonate resins are primarily tested from the viewpoints of transparency, strength and heat resistance. A problem in the attempt is a method for fixing the plastic sheet to a frame for vehicle. As described above, a fixing method such as bolting cannot be said to be highly appropriate from the viewpoint of stress concentration.
In the field of glass glazings for vehicles, a direct glazing method is already well known. The problem of stress concentration hardly occurs in the direct grading method. In the direct grading, a method using a specific two-component urethane adhesive is known (refer to disclosure of U.S. Pat. No. 5,853,895). An example of the adhesive is BETAMATE (trademark, product of Dow Automotive) which is commercially sold and known. It is also known that BETAMATE is a one-component or two-component urethane or epoxy adhesive system and can be used for adhesions of LEXAN (trademark, aromatic polycarbonate resin of General Electric Company) and of XENOY (trademark, polymer alloy resin of General Electric Company comprising an aromatic polycarbonate and a polybutylene terephthalate). A specific primer composition for enhancing the adhesion of an urethane sealant to a non-porous substrate such as glass or silicone hard coated resin glass is known (refer to JP-A 2001-064470 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”) and JP-A 2001-323214).
However, mere application of the direct glazing method to an aromatic polycarbonate resin sheet sometimes fails to provide a member such as metal to which an aromatic polycarbonate resin sheet is bonded nicely, and the wet heat resistance of the adhesive force in particular still needs to be improved.